INTRODUCTION: There have been significant technological advances for hemostasis in thyroid surgery, which allow more precise and safer vascular sealing than the traditional bond associated with mono- or bipolar electrocoagulation. OBJECTIVE: To compare the complications in total thyroidectomy using traditional techniques (ligation and electrocoagulation, including LigaSure) compared to the exclusive use of the Ultracision Harmonic scalpel, performing dissection, cutting and hemostasis simultaneously. METHODS: Retrospective descriptive non-randomized comparative study with 887 patients who underwent total thyroidectomy by the same surgeon. They were distributed into Group A (traditional techniques in 468 patients, January 1997 to September 2006) and Group B (Harmonic Ultracision in 419 patients, October 2006 to May 2010). RESULTS: There was a statistically-significant lower incidence of complications in Group B (0.95% versus 4.06% in group A): bleeding (0.24% versus 1.92% in group A), tracheostomy (0% versus 1.28%) and intensive care unit stay (0% versus 4.06%). Improvement of surgical activity parameters was also significant for Group B: shorter operation time (60minutes versus 180minutes), fewer hospital stays (4.62 versus 8.5 stays) and increase in operations per month (9.63 versus 4 interventions). Persistent sequelae (recurrent paralysis [0.48%] and hypoparathyroidism [0.47%]) decreased in the second group but the difference was not statistically significant compared to Group A. The cost per patient was lower in Group B CONCLUSIONS: The Ultracision Harmonic scalpel system is the technique of choice for thyroid surgery.